1. Field of the Invention
This invention relates to an image processing device and an image processing method.
2. Description of Related Art
Data of a document and the like, created by a user using an application, is in a form of vector data. The vector data is converted into page description language (PDL) data upon printing, and the converted data is sent to a printer. The PDL data is then rasterized in the printer into image data of a bitmap format, and the image data is printed out.
The higher the resolution of the image data becomes upon rasterization, the higher the definition of the image becomes upon drawing. However, the amount of data increases as the resolution becomes higher, so there is a case in which resolution upon rasterization can be selected from a plurality of different values of resolution according to image processing power.
For example, when writing resolution for a printing device of a printer is 1200 dpi, and if image processing power of the device is sufficiently high, image data can be generated upon rasterization at the same resolution as that in printing, i.e. 1200 dpi. On the other hand, when the image data is generated at resolution of 600 dpi, which is lower than 1200 dpi, upon rasterization, and then the resolution of the image data is converted from 600 dpi to 1200 dpi, an amount of the image data can be reduced and hence processing time can be shortened.
In the meantime, a technique of thinning image data after rasterization is known (see Japanese Patent Application Laid-Open Publication No. 2009-211376, and Japanese Patent Application Laid-Open Publication No. 2005-341249, for example). According printing characteristics of a printer, an object such as a character tends to thicken after printing; however, the thickening of the object can be improved by the thinning process.
In the case described above, in which the resolution of the image data upon rasterization is different from that at printing, the resolution of the image data is converted into resolution at a time of printing, and then the thinning process is performed on the obtained image data thereafter.
However, when image data which has been rasterized with low resolution is converted into the one with high resolution, the image of an object becomes thicker than in a case of the image data being rasterized with original high resolution. Therefore, the size of the object after the thinning process varies depending on the resolution at which the image data is rasterized.
A user expects that an image designed using vector data to be reproduced as it is after rasterization, regardless of the resolution at which the image data is rasterized. Thus, reproduction of identical images is required regardless of the resolution at which the image data is rasterized.